linux-stable.git/fs/backing-file.c, branch linux-rolling-lts Linux kernel stable tree fs: fix user path of nested backing files 2026-09-07T15:22:21+00:00 Baokun Li libaokun@linux.alibaba.com 2026-08-04T03:42:04+00:00 c03114634d342648bd34910aa8fb88007e92cc3c commit f2381b546e7e6a35c9fcee0d0ccb6c042a9aeb5d upstream. backing_file_open() derives the path to be stored in the new backing file from user_file->f_path. This is incorrect when user_file itself is a backing file, which is the case for nested stacking filesystems, e.g. overlayfs mounts where the lowerdir of one overlayfs is the merged directory of another. Since commit def3ae83da02 ("fs: store real path instead of fake path in backing file f_path") the f_path of a backing file holds the real path of the intermediate layer, not the path that the user opened. Commit 924577e4f6ca ("ovl: Fix nested backing file paths") fixed this for such configurations by passing file_user_path() from ovl_open_realfile(). However, commit 6af36aeb147a ("lsm: add backing_file LSM hooks") changed the first argument of backing_file_open() from the user path back to the user file and derived the path from user_file->f_path again, silently re-introducing the problem. As a result, files mapped through a nested overlayfs show the wrong path in /proc/<pid>/maps and in perf/ftrace mmap records. For example, with two nested overlayfs mounts: mkdir -p /ovl/{lower,upper,work,merged} /ovl/nested echo hello > /ovl/lower/foo mount -t overlay overlay \ -o lowerdir=/ovl/lower,upperdir=/ovl/upper,workdir=/ovl/work \ /ovl/merged # at least two lowerdirs are needed when upperdir is nonexistent mount -t overlay overlay \ -o lowerdir=/ovl/merged:/ovl/lower /ovl/nested mapping /ovl/nested/foo shows a disconnected path instead of the user path: # readlink /proc/self/fd/3 /ovl/nested/foo # grep foo /proc/self/maps 7f6e2c100000-7f6e2c101000 r--s 00000000 00:24 15813027 /foo The bogus path is derived from the f_path of the intermediate backing file, whose mount is a private clone that d_path() cannot resolve. Fix this by using file_user_path(), which returns the outermost user-visible path for backing files and falls back to &user_file->f_path for regular files. This restores the behavior of commit 924577e4f6ca ("ovl: Fix nested backing file paths") for overlayfs and also fixes the same problem for the other backing_file_open() callers, fuse passthrough and erofs ishare, when their user file is itself a backing file. backing_tmpfile_open() has the same pattern but is not affected: it is only called by ovl_create_tmpfile() for the upper layer, and another overlayfs is rejected as upperdir by the DCACHE_OP_REAL check in ovl_mount_dir_check(), so its user_file can never be a backing file. Fixes: 6af36aeb147a ("lsm: add backing_file LSM hooks") Cc: stable@vger.kernel.org Signed-off-by: Baokun Li <libaokun@linux.alibaba.com> Link: https://patch.msgid.link/20260804034204.3487077-1-libaokun@linux.alibaba.com Tested-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f2381b546e7e6a35c9fcee0d0ccb6c042a9aeb5d upstream.

backing_file_open() derives the path to be stored in the new backing
file from user_file->f_path.  This is incorrect when user_file itself
is a backing file, which is the case for nested stacking filesystems,
e.g. overlayfs mounts where the lowerdir of one overlayfs is the merged
directory of another.  Since commit def3ae83da02 ("fs: store real path
instead of fake path in backing file f_path") the f_path of a backing
file holds the real path of the intermediate layer, not the path that
the user opened.

Commit 924577e4f6ca ("ovl: Fix nested backing file paths") fixed this
for such configurations by passing file_user_path() from
ovl_open_realfile().  However, commit 6af36aeb147a ("lsm: add
backing_file LSM hooks") changed the first argument of
backing_file_open() from the user path back to the user file and
derived the path from user_file->f_path again, silently re-introducing
the problem.

As a result, files mapped through a nested overlayfs show the wrong
path in /proc/<pid>/maps and in perf/ftrace mmap records.  For example,
with two nested overlayfs mounts:

  mkdir -p /ovl/{lower,upper,work,merged} /ovl/nested
  echo hello > /ovl/lower/foo
  mount -t overlay overlay \
	-o lowerdir=/ovl/lower,upperdir=/ovl/upper,workdir=/ovl/work \
	/ovl/merged
  # at least two lowerdirs are needed when upperdir is nonexistent
  mount -t overlay overlay \
	-o lowerdir=/ovl/merged:/ovl/lower /ovl/nested

mapping /ovl/nested/foo shows a disconnected path instead of the user
path:

  # readlink /proc/self/fd/3
  /ovl/nested/foo
  # grep foo /proc/self/maps
  7f6e2c100000-7f6e2c101000 r--s 00000000 00:24 15813027 /foo

The bogus path is derived from the f_path of the intermediate backing
file, whose mount is a private clone that d_path() cannot resolve.

Fix this by using file_user_path(), which returns the outermost
user-visible path for backing files and falls back to
&user_file->f_path for regular files.  This restores the behavior of
commit 924577e4f6ca ("ovl: Fix nested backing file paths") for
overlayfs and also fixes the same problem for the other
backing_file_open() callers, fuse passthrough and erofs ishare, when
their user file is itself a backing file.

backing_tmpfile_open() has the same pattern but is not affected: it is
only called by ovl_create_tmpfile() for the upper layer, and another
overlayfs is rejected as upperdir by the DCACHE_OP_REAL check in
ovl_mount_dir_check(), so its user_file can never be a backing file.

Fixes: 6af36aeb147a ("lsm: add backing_file LSM hooks")
Cc: stable@vger.kernel.org
Signed-off-by: Baokun Li <libaokun@linux.alibaba.com>
Link: https://patch.msgid.link/20260804034204.3487077-1-libaokun@linux.alibaba.com
Tested-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
lsm: add backing_file LSM hooks 2026-07-04T11:44:14+00:00 Paul Moore paul@paul-moore.com 2026-06-26T07:50:34+00:00 5dfcb15974e7d0f96aca278dd9f1b85df91523ef [ Upstream commit 6af36aeb147a06dea47c49859cd6ca5659aeb987 ] Stacked filesystems such as overlayfs do not currently provide the necessary mechanisms for LSMs to properly enforce access controls on the mmap() and mprotect() operations. In order to resolve this gap, a LSM security blob is being added to the backing_file struct and the following new LSM hooks are being created: security_backing_file_alloc() security_backing_file_free() security_mmap_backing_file() The first two hooks are to manage the lifecycle of the LSM security blob in the backing_file struct, while the third provides a new mmap() access control point for the underlying backing file. It is also expected that LSMs will likely want to update their security_file_mprotect() callback to address issues with their mprotect() controls, but that does not require a change to the security_file_mprotect() LSM hook. There are a three other small changes to support these new LSM hooks: * Pass the user file associated with a backing file down to alloc_empty_backing_file() so it can be included in the security_backing_file_alloc() hook. * Add getter and setter functions for the backing_file struct LSM blob as the backing_file struct remains private to fs/file_table.c. * Constify the file struct field in the LSM common_audit_data struct to better support LSMs that need to pass a const file struct pointer into the common LSM audit code. Thanks to Arnd Bergmann for identifying the missing EXPORT_SYMBOL_GPL() and supplying a fixup. Cc: stable@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org Cc: linux-unionfs@vger.kernel.org Cc: linux-erofs@lists.ozlabs.org Reviewed-by: Amir Goldstein <amir73il@gmail.com> Reviewed-by: Serge Hallyn <serge@hallyn.com> Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Paul Moore <paul@paul-moore.com> [Mainline declares lsm_backing_file_cache in security/lsm.h. Linux 6.18.y does not have security/lsm_init.c or security/lsm.h; the cache variable is defined locally as static struct kmem_cache *lsm_backing_file_cache in security/security.c.] Signed-off-by: Cai Xinchen <caixinchen1@huawei.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 6af36aeb147a06dea47c49859cd6ca5659aeb987 ]

Stacked filesystems such as overlayfs do not currently provide the
necessary mechanisms for LSMs to properly enforce access controls on the
mmap() and mprotect() operations.  In order to resolve this gap, a LSM
security blob is being added to the backing_file struct and the following
new LSM hooks are being created:

 security_backing_file_alloc()
 security_backing_file_free()
 security_mmap_backing_file()

The first two hooks are to manage the lifecycle of the LSM security blob
in the backing_file struct, while the third provides a new mmap() access
control point for the underlying backing file.  It is also expected that
LSMs will likely want to update their security_file_mprotect() callback
to address issues with their mprotect() controls, but that does not
require a change to the security_file_mprotect() LSM hook.

There are a three other small changes to support these new LSM hooks:
* Pass the user file associated with a backing file down to
alloc_empty_backing_file() so it can be included in the
security_backing_file_alloc() hook.
* Add getter and setter functions for the backing_file struct LSM blob
as the backing_file struct remains private to fs/file_table.c.
* Constify the file struct field in the LSM common_audit_data struct to
better support LSMs that need to pass a const file struct pointer into
the common LSM audit code.

Thanks to Arnd Bergmann for identifying the missing EXPORT_SYMBOL_GPL()
and supplying a fixup.

Cc: stable@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-unionfs@vger.kernel.org
Cc: linux-erofs@lists.ozlabs.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>
[Mainline declares lsm_backing_file_cache in security/lsm.h.  Linux 6.18.y
does not have security/lsm_init.c or security/lsm.h; the cache variable
is defined locally as static struct kmem_cache *lsm_backing_file_cache in
security/security.c.]
Signed-off-by: Cai Xinchen <caixinchen1@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Merge tag 'vfs-6.17-rc1.mmap_prepare' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs 2025-07-28T20:43:25+00:00 Linus Torvalds torvalds@linux-foundation.org 2025-07-28T20:43:25+00:00 7031769e102b768b3fa0c4c726faf532cb31e973 Pull mmap_prepare updates from Christian Brauner: "Last cycle we introduce f_op->mmap_prepare() in c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file callback"). This is preferred to the existing f_op->mmap() hook as it does require a VMA to be established yet, thus allowing the mmap logic to invoke this hook far, far earlier, prior to inserting a VMA into the virtual address space, or performing any other heavy handed operations. This allows for much simpler unwinding on error, and for there to be a single attempt at merging a VMA rather than having to possibly reattempt a merge based on potentially altered VMA state. Far more importantly, it prevents inappropriate manipulation of incompletely initialised VMA state, which is something that has been the cause of bugs and complexity in the past. The intent is to gradually deprecate f_op->mmap, and in that vein this series coverts the majority of file systems to using f_op->mmap_prepare. Prerequisite steps are taken - firstly ensuring all checks for mmap capabilities use the file_has_valid_mmap_hooks() helper rather than directly checking for f_op->mmap (which is now not a valid check) and secondly updating daxdev_mapping_supported() to not require a VMA parameter to allow ext4 and xfs to be converted. Commit bb666b7c2707 ("mm: add mmap_prepare() compatibility layer for nested file systems") handles the nasty edge-case of nested file systems like overlayfs, which introduces a compatibility shim to allow f_op->mmap_prepare() to be invoked from an f_op->mmap() callback. This allows for nested filesystems to continue to function correctly with all file systems regardless of which callback is used. Once we finally convert all file systems, this shim can be removed. As a result, ecryptfs, fuse, and overlayfs remain unaltered so they can nest all other file systems. We additionally do not update resctl - as this requires an update to remap_pfn_range() (or an alternative to it) which we defer to a later series, equally we do not update cramfs which needs a mixed mapping insertion with the same issue, nor do we update procfs, hugetlbfs, syfs or kernfs all of which require VMAs for internal state and hooks. We shall return to all of these later" * tag 'vfs-6.17-rc1.mmap_prepare' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: doc: update porting, vfs documentation to describe mmap_prepare() fs: replace mmap hook with .mmap_prepare for simple mappings fs: convert most other generic_file_*mmap() users to .mmap_prepare() fs: convert simple use of generic_file_*_mmap() to .mmap_prepare() mm/filemap: introduce generic_file_*_mmap_prepare() helpers fs/xfs: transition from deprecated .mmap hook to .mmap_prepare fs/ext4: transition from deprecated .mmap hook to .mmap_prepare fs/dax: make it possible to check dev dax support without a VMA fs: consistently use can_mmap_file() helper mm/nommu: use file_has_valid_mmap_hooks() helper mm: rename call_mmap/mmap_prepare to vfs_mmap/mmap_prepare 
Pull mmap_prepare updates from Christian Brauner:
 "Last cycle we introduce f_op->mmap_prepare() in c84bf6dd2b83 ("mm:
  introduce new .mmap_prepare() file callback").

  This is preferred to the existing f_op->mmap() hook as it does require
  a VMA to be established yet, thus allowing the mmap logic to invoke
  this hook far, far earlier, prior to inserting a VMA into the virtual
  address space, or performing any other heavy handed operations.

  This allows for much simpler unwinding on error, and for there to be a
  single attempt at merging a VMA rather than having to possibly
  reattempt a merge based on potentially altered VMA state.

  Far more importantly, it prevents inappropriate manipulation of
  incompletely initialised VMA state, which is something that has been
  the cause of bugs and complexity in the past.

  The intent is to gradually deprecate f_op->mmap, and in that vein this
  series coverts the majority of file systems to using f_op->mmap_prepare.

  Prerequisite steps are taken - firstly ensuring all checks for mmap
  capabilities use the file_has_valid_mmap_hooks() helper rather than
  directly checking for f_op->mmap (which is now not a valid check) and
  secondly updating daxdev_mapping_supported() to not require a VMA
  parameter to allow ext4 and xfs to be converted.

  Commit bb666b7c2707 ("mm: add mmap_prepare() compatibility layer for
  nested file systems") handles the nasty edge-case of nested file
  systems like overlayfs, which introduces a compatibility shim to allow
  f_op->mmap_prepare() to be invoked from an f_op->mmap() callback.

  This allows for nested filesystems to continue to function correctly
  with all file systems regardless of which callback is used. Once we
  finally convert all file systems, this shim can be removed.

  As a result, ecryptfs, fuse, and overlayfs remain unaltered so they
  can nest all other file systems.

  We additionally do not update resctl - as this requires an update to
  remap_pfn_range() (or an alternative to it) which we defer to a later
  series, equally we do not update cramfs which needs a mixed mapping
  insertion with the same issue, nor do we update procfs, hugetlbfs,
  syfs or kernfs all of which require VMAs for internal state and hooks.
  We shall return to all of these later"

* tag 'vfs-6.17-rc1.mmap_prepare' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  doc: update porting, vfs documentation to describe mmap_prepare()
  fs: replace mmap hook with .mmap_prepare for simple mappings
  fs: convert most other generic_file_*mmap() users to .mmap_prepare()
  fs: convert simple use of generic_file_*_mmap() to .mmap_prepare()
  mm/filemap: introduce generic_file_*_mmap_prepare() helpers
  fs/xfs: transition from deprecated .mmap hook to .mmap_prepare
  fs/ext4: transition from deprecated .mmap hook to .mmap_prepare
  fs/dax: make it possible to check dev dax support without a VMA
  fs: consistently use can_mmap_file() helper
  mm/nommu: use file_has_valid_mmap_hooks() helper
  mm: rename call_mmap/mmap_prepare to vfs_mmap/mmap_prepare
fs: constify file ptr in backing_file accessor helpers 2025-07-18T09:09:29+00:00 Amir Goldstein amir73il@gmail.com 2025-06-07T11:53:03+00:00 4e301d858af17ae2ce56886296e5458c5a08219a Add internal helper backing_file_set_user_path() for the only two cases that need to modify backing_file fields. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Link: https://lore.kernel.org/20250607115304.2521155-2-amir73il@gmail.com Signed-off-by: Christian Brauner <brauner@kernel.org> 
Add internal helper backing_file_set_user_path() for the only
two cases that need to modify backing_file fields.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/20250607115304.2521155-2-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
fs: consistently use can_mmap_file() helper 2025-06-17T11:47:22+00:00 Lorenzo Stoakes lorenzo.stoakes@oracle.com 2025-06-16T19:33:22+00:00 b013ed403197f3f8c30ddb3ce66fe05a632b3493 Since commit c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file callback"), the f_op->mmap() hook has been deprecated in favour of f_op->mmap_prepare(). Additionally, commit bb666b7c2707 ("mm: add mmap_prepare() compatibility layer for nested file systems") permits the use of the .mmap_prepare() hook even in nested filesystems like overlayfs. There are a number of places where we check only for f_op->mmap - this is incorrect now mmap_prepare exists, so update all of these to use the general helper can_mmap_file(). Most notably, this updates the elf logic to allow for the ability to execute binaries on filesystems which have the .mmap_prepare hook, but additionally we update nested filesystems. Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Link: https://lore.kernel.org/b68145b609532e62bab603dd9686faa6562046ec.1750099179.git.lorenzo.stoakes@oracle.com Acked-by: Kees Cook <kees@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org> 
Since commit c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file
callback"), the f_op->mmap() hook has been deprecated in favour of
f_op->mmap_prepare().

Additionally, commit bb666b7c2707 ("mm: add mmap_prepare() compatibility
layer for nested file systems") permits the use of the .mmap_prepare() hook
even in nested filesystems like overlayfs.

There are a number of places where we check only for f_op->mmap - this is
incorrect now mmap_prepare exists, so update all of these to use the
general helper can_mmap_file().

Most notably, this updates the elf logic to allow for the ability to
execute binaries on filesystems which have the .mmap_prepare hook, but
additionally we update nested filesystems.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/b68145b609532e62bab603dd9686faa6562046ec.1750099179.git.lorenzo.stoakes@oracle.com
Acked-by: Kees Cook <kees@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
mm: rename call_mmap/mmap_prepare to vfs_mmap/mmap_prepare 2025-06-17T11:35:23+00:00 Lorenzo Stoakes lorenzo.stoakes@oracle.com 2025-06-16T19:33:20+00:00 20ca475d9860e14cf389f5a7d5ba9c6437d74613 The call_mmap() function violates the existing convention in include/linux/fs.h whereby invocations of virtual file system hooks is performed by functions prefixed with vfs_xxx(). Correct this by renaming call_mmap() to vfs_mmap(). This also avoids confusion as to the fact that f_op->mmap_prepare may be invoked here. Also rename __call_mmap_prepare() function to vfs_mmap_prepare() and adjust to accept a file parameter, this is useful later for nested file systems. Finally, fix up the VMA userland tests and ensure the mmap_prepare -> mmap shim is implemented there. Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Link: https://lore.kernel.org/8d389f4994fa736aa8f9172bef8533c10a9e9011.1750099179.git.lorenzo.stoakes@oracle.com Signed-off-by: Christian Brauner <brauner@kernel.org> 
The call_mmap() function violates the existing convention in
include/linux/fs.h whereby invocations of virtual file system hooks is
performed by functions prefixed with vfs_xxx().

Correct this by renaming call_mmap() to vfs_mmap(). This also avoids
confusion as to the fact that f_op->mmap_prepare may be invoked here.

Also rename __call_mmap_prepare() function to vfs_mmap_prepare() and adjust
to accept a file parameter, this is useful later for nested file systems.

Finally, fix up the VMA userland tests and ensure the mmap_prepare -> mmap
shim is implemented there.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/8d389f4994fa736aa8f9172bef8533c10a9e9011.1750099179.git.lorenzo.stoakes@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
tree-wide: s/revert_creds_light()/revert_creds()/g 2024-12-02T10:25:09+00:00 Christian Brauner brauner@kernel.org 2024-11-25T14:10:02+00:00 51c0bcf0973a3836adfc46f30f876f412478e376 Rename all calls to revert_creds_light() back to revert_creds(). Link: https://lore.kernel.org/r/20241125-work-cred-v2-6-68b9d38bb5b2@kernel.org Reviewed-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Christian Brauner <brauner@kernel.org> 
Rename all calls to revert_creds_light() back to revert_creds().

Link: https://lore.kernel.org/r/20241125-work-cred-v2-6-68b9d38bb5b2@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
tree-wide: s/override_creds_light()/override_creds()/g 2024-12-02T10:25:09+00:00 Christian Brauner brauner@kernel.org 2024-11-25T14:10:01+00:00 6771e004b40962402d0e973fc7d2e0e61364fdfb Rename all calls to override_creds_light() back to overrid_creds(). Link: https://lore.kernel.org/r/20241125-work-cred-v2-5-68b9d38bb5b2@kernel.org Reviewed-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Christian Brauner <brauner@kernel.org> 
Rename all calls to override_creds_light() back to overrid_creds().

Link: https://lore.kernel.org/r/20241125-work-cred-v2-5-68b9d38bb5b2@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
fs/backing_file: fix wrong argument in callback 2024-11-26T17:13:29+00:00 Amir Goldstein amir73il@gmail.com 2024-11-26T14:53:42+00:00 2957fa4931a3b658d8e54eda9439d4c57967e8ad Commit 48b50624aec4 ("backing-file: clean up the API") unintentionally changed the argument in the ->accessed() callback from the user file to the backing file. Fixes: 48b50624aec4 ("backing-file: clean up the API") Reported-by: syzbot+8d1206605b05ca9a0e6a@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-unionfs/67447b3c.050a0220.1cc393.0085.GAE@google.com/ Tested-by: syzbot+8d1206605b05ca9a0e6a@syzkaller.appspotmail.com Signed-off-by: Amir Goldstein <amir73il@gmail.com> Link: https://lore.kernel.org/r/20241126145342.364869-1-amir73il@gmail.com Acked-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Christian Brauner <brauner@kernel.org> 
Commit 48b50624aec4 ("backing-file: clean up the API") unintentionally
changed the argument in the ->accessed() callback from the user file to
the backing file.

Fixes: 48b50624aec4 ("backing-file: clean up the API")
Reported-by: syzbot+8d1206605b05ca9a0e6a@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-unionfs/67447b3c.050a0220.1cc393.0085.GAE@google.com/
Tested-by: syzbot+8d1206605b05ca9a0e6a@syzkaller.appspotmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20241126145342.364869-1-amir73il@gmail.com
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
fs/backing-file: Convert to revert/override_creds_light() 2024-11-11T09:45:04+00:00 Vinicius Costa Gomes vinicius.gomes@intel.com 2024-11-07T00:57:18+00:00 d06ffd63a01226e9f741245ebac9b8f562fa04f5 As the credentials used by backing-file are long lived in relation to the critical section (override_creds() -> revert_creds()) we can replace them by their lighter alternatives. Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> 
As the credentials used by backing-file are long lived in relation to
the critical section (override_creds() -> revert_creds()) we can
replace them by their lighter alternatives.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>